Manganese Sulfide (MnS) Nanocrystals: Synthesis, Properties, and Applications

Manganese(II) sulfide (MnS) is an interesting material for both fundamental and applicative research, especially when its bulk properties are modulated or augmented by reducing the size into the nanometric region (< 100 nm). Indeed, due to its polymorphism, MnS is an attractive material to understand factors determining which crystal structure forms and to develop synthetic strategies for polymorphism control. We have reviewed the literature concerning MnS nanosystems having at least one dimension smaller than 100 nm. Successful synthetic techniques for the preparation of zero- and one-dimensional MnS nanosystems (either homogeneous and heterogeneous) with size, shape, and polymorphism control are presented with particular emphasis on solvothermal techniques and on studies devoted to understanding the growth mechanism and the polymorphism. Properties and applications are separately collected in three broad areas corresponding to nanosize MnS used as an optical, electric, and magnetic material. Indeed, MnS has attracting properties such as its large (ca. 3 eV) bandgap, which makes it promising for emission in the ultraviolet region. The magnetic properties have also arisen attention since MnS is antiferromagnetic at low temperature and (super)paramagnetic at room temperature. Finally, the layered structure of the hexagonal ? polymorph, in addition to the chemical stability and insolubility of MnS, is responsible for the good performance as a lithium-ion battery electrode or supercapacitor material since the insertion/exchange of small ions is particularly easy.